The invention described herein may be manufactured and used by or for the Government of the United States for all governmental purposes without the payment of any royalty.
The present invention relates to a tilting wing aircraft. More particularly, the invention relates to a compound tilting wing aircraft.
Several aircraft use tilting wing configurations to maximize the use of the wing surface for lift generation. Such configurations typically are combined with separate longitudinal and lateral control surfaces (tail) and/or control devices mounted separately on the aircraft to provide rotational control about the principle axes of flight. Rotational control (pitch and yaw) is most critical when the center-of-rotation is expected to vary appreciably, or during low airspeed flight e.g. conventional takeoff and landing (CTOL), short takeoff and landing (STOL) and vertical takeoff and landing (VTOL). For STOL and VTOL conditions, conventional tilting wing configurations derive pitch and yaw control power through large vertical and horizontal tail surfaces, tail rotors, or a combination of the two. The requirement of conventional STOL/VTOL tail aft aircraft configurations to have an out-sized empennage (horizontal and vertical tail) and/or a tail rotor system used only during low airspeed flight conditions is due to the high lift generated during such conditions creating large, negative downwash angles at the horizontal tail. The downwash tends to destabilize such configurations in pitch. Additionally, such configurations incur substantial weight and drag penalties, which translate into reduced payload or cruise performance, as compared to CTOL configurations. Further, the additional control devices increase cost due to mechanical complexity, construction and maintenance.
Therefore, there exists a need in the art for a tilting wing configuration which maximizes control power and lift for a fixed wing area while reducing vehicle drag, weight penalties and costs due to mechanical complexity, maintenance, and construction.
The principal object of the present invention is to provide an aircraft with a compound tilting wing (CTW), which maximizes control power and lift for a fixed wing area while reducing vehicle drag and weight penalties.
According to one aspect of the invention, the invention is an aircraft including a fuselage, a CTW and aircraft engines mounted on the aircraft.
According to another aspect of the invention, the CTW includes a leading edge wing portion and a tilting main wing portion. The leading edge wing portion and the tilting main wing portion each include a leading edge, a trailing edge, a chord, a lower surface and an upper surface.
According to yet another aspect of the invention, the tilting main wing portion fits conformably with the leading edge wing portion forming an aerodynamically single wing in a cruise flight position.
According to another aspect of the invention, the tilting main wing portion may be rotated from the cruise flight position to various low airspeed flight positions including a position nearly perpendicular to the upper surface of the fuselage such that stabilizing center of gravity travel augments a pitch control authority.